The present invention relates to color fading a dyed textile material, and more particularly to selectively decreasing laser energy density per unit area adjacent the periphery of an area selected to be faded.
A laser beam can interact with a surface in a number of ways to change the surface properties, including light absorption, photon scattering and impact. For example, a surface may be burned by an intense laser beam. Some surface particles may be ablated from a surface by the impact of a laser beam. Therefore, a surface can be treated with one or more proper lasers to achieve certain effects that may not be easily done with other methods. One example is described in a U.S. Pat. No. 5,567,207, titled xe2x80x9cMethod For Marking And Fading Textiles With Lasersxe2x80x9d, issuing on Oct. 22, 1996 and is incorporated herein by reference. Similarly, U.S. Pat. No. 6,140,602, entitled Marking Of Fabrics And Other Materials Using A Laser issuing Oct. 31, 2000 to Costin; U.S. Pat. No. 6,002,099 entitled User Control Interface For Laser Simulating Sandblasting Apparatus, issuing Dec. 14, 1999; and U.S. Pat. No. 5,916,461 entitled System And Method For Processing Surfaces By A Laser, issuing Jun. 29, 1999 to Costin et al. Hereby incorporated by reference.
Although other traditional methods, such as dyeing, printing, weaving, embossing and stamping, have been widely used, laser methods appear to have certain advantages in producing complex and intricate graphics on the materials. This is at least in part because many of the traditional methods lack the necessary registration and precision to insure that minute details of the graphics are accurately and repeatably presented on the materials. In addition, laser methods obviate many problems associated with the traditional methods such as high cost of equipment manufacturing, equipment maintenance, and operation, and environmental problems.
Denim fabrics may undergo a sandblasting process to obtain a worn look. Denim jeans are often sold with a worn look in the upper knee portions and back seat portion. The effect is similar to a feathered or shadowed look in which the degree of the worn look continuously changes along the length and width of the seemingly xe2x80x9cwornxe2x80x9d areas.
A sandblast treatment conventionally abrades the jeans with sand particles, metal particles or other materials at selected areas to impart a worn look with a desired degree of wear. This process blasts sand particles from a sandblasting device to a pair of jeans. The random spatial distribution of the sand creates a unique appearance in a treated area. Denim jeans and other clothing treated with such a sandblast process have been very popular in the consumer market.
However, the sandblast process has a number of problems and limitations. For example, the process of blasting sand or other abrasive particles presents significant environmental issues. A worker usually needs to wear protective gear and masks to reduce the impact of inhaling any airborne sand or other abrasive particles that are used. The actual blasting process typically occurs in a room which is shielded from other areas in a manufacturing facility. Further environmental issues arise with the clean up and disposal of the sand. In practice, undesired sand is rarely completely eliminated from the pockets of the denim jeans or jackets.
The sandblasting process is an abrasive process, which causes wear to the sandblasting equipment. Typically, the actual equipment needs to be replaced as often as after one year of normal operation. This can result in added capital expense and installation.
In addition, the actual cost of the sandblasting process is estimated as high as several dollars per unit garment depending upon capacity utilization. This high cost is at least in part due to the labor involved, the cost of the equipment repair or continual purchase, the environmental clean-up required, the sand used, and actual yield of the goods. Furthermore, the sandblasting process can adversely affect the strength and durability of the finished goods due to the abrasion of the sand or other particles that are used.
Despite the above problems and limitations, the sandblast process is still in wide use simply because there is no other alternative technique that can economically produce the desired surface appearance of the sandblast treatment. In view of the above, the inventors found it desirable to replace the sandblast process with a new environmentally friendly process which is capable of producing the xe2x80x9csandblast lookxe2x80x9d, while reducing the cost and maintaining the durability of the finished goods.
The present invention provides an apparatus and method of treating a dyed material, wherein an unfocussed, scanning laser is passed through a mask such that a portion of the mask intersects the scanning pattern. The present invention is particularly suited to creating abrasion type fading of the sheet material. That is, the system can replicate an abraded portion of the sheet material.
In one configuration, the invention includes a support surface spaced from a scanning laser. The scanning laser is selected to project a laser beam along an optical path, wherein the optical path intersects the support surface. In addition, the scanning laser follows a given pattern or trace. A lens is disposed in the optical path intermediate the scanning laser and the support surface. The lens is selected to focus the laser beam along the optical path to a focal point. The present invention locates a mask in the optical path intermediate the lens and the focal point, the mask selected to partially occlude the given pattern. Thus, the mask is disposed intermediate the scanning laser and the focal point. By partially occluding the laser .beam prior to the focal point, the mask effectively attenuates the amount of energy impinging the sheet material at the edge of a desired pattern. Thus, by employing a mask having an aperture corresponding the shape of the desired image to be formed, the edge of the resulting image can be formed to include transition or fade from the image to the appearance of the untreated sheet material.
In further configurations, the mask is formed of a laser opaque material and includes an aperture through which a portion of the laser beam passes. The aperture in the mask can be formed to have a continuous periphery. In a further construction, the aperture in the mask is defined by a plurality of linear segments, such as saw tooth or zigzag. However, it is understood the linear segments could be curvilinear, straight or a combination of both. Thus, the present invention can be utilized to form an area of generally uniform fading, wherein the area of fading transitions to the background color in a controlled transition.